1. Field of the Invention
2. Description of Related Art
A conventional ratchet wrench comprises a handle and a head at one end of the handle. The head has a receive hole, a first chamber and a second chamber. A driving member is received in the receive hole of the head for free rotating. The driving member has a teeth portion at outer surface thereof. A pawl has a teeth portion at one side thereof and a driven portion at the other side thereof. The pawl is received in the first chamber of the head while the teeth portion of the pawl meshes with the teeth portion of the driving member. A switch device has a body and a turning piece. The body of the switch device is received in the second chamber of the head and movable between a first position and a second position. The body has an elastic driving device disposed therein to be against the driven portion of the pawl.
As described above, the pawl is configured to engage with the driving member to prevent the driving member from being rotated reversely. However, the teeth portion of the pawl of the conventional ratchet wrench is going to be fully engaged with the teeth portion of the driving member, and that requires higher standard of machining. Furthermore, the teeth portion of the pawl of the conventional ratchet wrench and the teeth portion of the driving member are easily worn out. Besides, the teeth portion may be collapsed easily.
US 2003/0150299 to Chen and US 2004/0083860 to Arnold et al. disclose a ratchet wrench, wherein the teeth of the pawl of the ratchet wrench of Arnold et al. has a specific arrangement relative to the teeth of the gear ring when the pawl is shifted to either of two ends of the compartment in which the pawl is located, as disclosed in FIGS. 4A and 4C. Specifically, when the pawl is shifted to the right end of the compartment, a radial distance is formed between the left end of the pawl and the gear ring. Similarly, when the pawl is shifted to the left end of the compartment, another radial distance is formed between the right end of the pawl and the gear ring. By this arrangement, the pawl is easily shifted its direction and reduces wearing. In order to achieve the radial distance between either of the two ends of the pawl and the gear ring, the shape or curvature of the pawl needs to be precisely machined, and the potential manufacturing cost is increased.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional ratchet wrench.